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Selection of Device, Administration of Bronchodilator, and Evaluation of Response to Therapy in Mechanically Ventilated Patients

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Selection of Device, Administration of Bronchodilator, and Evaluation of Response to Therapy in Mechanically Ventilated Patients AARC Clinical Practice Guideline Selection of Device, Administration of Bronchodilator, and Evaluation of Response to Therapy in Mechanically Ventilated Patients BDMV 1.0 PROCEDURE: mechanically ventilated adult patients (1.0-15.3 Device selection, bronchodilator administration, %) compared to nonintubated, ambulatory and evaluation of response to therapy during me- adult subjects in ambulatory adult patients (10- chanical ventilation. The reader is referred to previ- 14%).22 ously published Guidelines addressing aspects of 2.3.1 In-vivo studies of aerosol deposition aerosol administration and delivery.1-4 from nebulizers during mechanical venti- lation report 1.2%,23 2.22%,24 2.9%,25 and BDMV 2.0 DESCRIPTION: 15.3%26 in adults, and 0.22% in infants.27 The selection of a device and strategy for adminis- Similar studies using MDI reported 6- tration, the administration, and the evaluation of re- 11%23,28 in adults and 0.9 in infants.27 sponse of patients to bronchodilator aerosol during 2.3.2 Factors that affect lower respiratory mechanical ventilation. tract deposition include: aerosol device selected,7,10,23,24,29 how it is operated,24,26,30-32 2.1 Devices include metered dose inhaler its placement in relation to the ventilator (MDI) with adapter and chamber or inline circuit/patient,33 the ventilator selected,34 elbow and catheter; pneumatic nebulizer; small the ventilator settings and mode of venti- volume nebulizer (SVN) large volume nebuliz- lation,35 humidity,32,35 drug formulation, er (LVN); ultrasonic nebulizer. (Although expe- drug dose, and caliber of the airway.29,36-38 rience suggests that inhalers that dispense dry 2.3.3 Assessment is necessary to deter- powder are not suitable for use in ventilator cir- mine the appropriate dose, optimal fre- cuits, a recent bench study reports positive re- quency of administration, and overall re- sults and suggests clinical trials.5 Such use can- sponse to therapy.7,39 An empirical trial of not yet be recommended.) bronchodilator is recommended in any 2.2 Aerosolized bronchodilators have been mechanically ventilated patient in whom shown to be effective in adults, children, and a potential indication exists.40 infants receiving mechanical ventilation.6-21 In- 2.4 Because delivery is reduced, increased haled beta-adrenergic7-17 and anticholinergic doses may be required to provide desired or op- bronchodilators17,18 are effectiveRETIRED in mechanical- timal effect. Patients should be monitored to ly ventilated patients. Inhaled isoproterenol hy- determine effect of dose and to support initial drochloride,15,16 isoetharine mesylate,17 metapro- and continued treatment.7-10,32. terenol sulfate,18 fenoterol,19 and albuterol7-12,14 can all produce clinically important bronchodi- BDMV3.0 SETTING: lation. In ventilator-supported COPD patients, Aerosolized bronchodilator therapy via mechanical fenoterol in combination with ipratropium bro- ventilator can be provided in a number of settings mide was more effective than ipratropium including: hospital, home, and subacute or extend- alone.14 Inhaled beta adrenergic and anticholin- ed care facility. ergic drugs are effective in ventilated infants and neonates with acute, subacute, and chronic BDMV 4.0 INDICATIONS: lung disease.18-20 Bronchodilator aerosol administration and evalua- 2.3 Aerosol deposition in the lung has, in gen- tion of response are indicated whenever bron- eral, been shown to be reduced in intubated, choconstriction or increased airways resistance is RESPIRATORY CARE • JANUARY 1999 VOL 44 NO 1 105 AARC GUIDELINE: SELECTION OF DEVICE documented or suspected in patients during me- 6.6.1 Addition of gas to the ventilator cir- chanical ventilation: cuit from a nebulizer may increase vol- umes, flows, and peak airway pressures, BDMV 5.0 CONTRAINDICATIONS: thus altering the intended pattern of venti- 5.1 Some assessment maneuvers may be con- lation. Ventilator setting adjustments traindicated for patients in extremis (eg, pro- made to accommodate the additional gas longed inspiratory pause for patients with high flow during nebulization must be reset at auto-PEEP). the end of the treatment. 5.2 Certain medications may be contraindicated 6.6.2 Addition of gas from a nebulizer in some patients. Consult the package insert for into the ventilator circuit may result in the product-specific contraindications. patient’s becoming unable to trigger the ventilator during nebulization,47 leading to BDMV 6.0 HAZARDS/COMPLICATIONS: hypoventilation. 6.1 Specific assessment procedures may have 6.7 At least one early anecdotal report de- inherent hazards or complications: (eg, inspira- scribed cardiac toxicity due to CFCs used as tory pause, expiratory pause).41-44 propellants in MDIs.48 Adverse cardiac effects 6.2 Inappropriate device selection or inappro- are unlikely to occur with doses recommended priate use of device and/or technique variables in clinical practice because of the short half life may result in underdosing.7 of CFCs in the blood (< 40 s), particularly when 6.3 Device malfunction may result in reduced at least a short interval is maintained between drug delivery and may possibly compromise successive doses.49 the integrity of the ventilator circuit.45,46 6.4 Complications of specific pharmacologic BDMV 7.0 LIMITATIONS OF PROCEDURE agents. Higher doses of beta agonists delivered OR DEVICE: by an MDI or nebulizer may cause adverse ef- 7.1 During mechanical ventilation, the deposi- fects secondary to systemic absorption of the tion of drug to the lower respiratory tract is re- drug or propellants. The potential for hy- duced. Doses should be adjusted to compensate pokalemia and atrial and ventricular dysrhyth- for reduced delivery. Variables should be opti- mias may exist with high doses in critically ill mized to enhance medication delivery. patients.47-49 7.2 Ventilator modes and settings can affect de- 6.5 Aerosol medication, propellants, or cold, position. Lung-model studies suggest that low dry gas that bypasses the natural upper respira- inspiratory flows, use of decelerating flow in- tory tract may cause bronchospasm or irritation stead of square wave, tidal volume > 500 mL, of the airway.47-50 Although the efficiency of and increased duty cycle (inspiratory phase) are aerosol delivery from an MDI can be increased all associated with improved aerosol deposi- by actuating the canister into a narrow gauge tion.24,26,30,31 Spontaneous inspiration through the catheter with the catheter positionedRETIRED at the end ventilator circuit increased lung deposition of the endotracheal tube. A study in rabbits29 has compared to controlled, assist/control and pres- shown that such introduction produces necro- sure support ventilation.35 tizing inflammation and mucosal ulceration, 7.3 Humidification of inspired gas during me- probably from the topical effect of the oleic chanical ventilation reduces aerosol deposition to acid used for its surfactant property and the the lower respiratory tract by approximately chlorofluorocarbons (CFCs). Such administra- 40%.32,35 Because these in vitro studies suggest tion is not recommended. The results of further that humidity markedly decreases aerosol, the al- study are needed to support or condemn this ternatives are to bypass the humidifier during practice. aerosol therapy, which may dry the airway and 6.6 The aerosol device or adapter used and offset the effect of the increased delivery, or to re- technique of operation may affect ventilator tain the humidifier and increase the dose of bron- performance characteristics and/or alter the chodilator. It is probably better to retain the hu- sensitivity of the alarm systems. midifier and increase the dose of bronchodilator. 106 RESPIRATORY CARE • JANUARY 1999 VOL 44 NO 1 AARC GUIDELINE: SELECTION OF DEVICE 7.4 Placement of the aerosol device in the ven- vivo experiments have associated tilator circuit affects the amount of drug deliv- endothelial damage at the carina in ered to the lungs.33. Placing the nebulizer 30 cm response to temperature and ingredi- from the endotracheal tube is more efficient ents (oleic acid) of the aerosol.50 In- than placing it between the patient Y and the sufficient data are available to sup- endotracheal tube because the tubing acts as a port clinical use of such devices at reservoir for accumulation of aerosol between this time.50,54 inspirations.15,16,28 If an artificial nose is in use, it 7.6.1.4 MDI actuation is performed should be removed during aerosol administra- manually and should be synchro- tion.51 nized with the beginning of inspira- 7.5 Coordination of aerosol generation with tion.32,35 Actuating an MDI out of ventilator triggering (initiation of inspiratory synchrony with the inspiratory air- gas flow) improves delivery of drug to the flow has been shown to result in lung.31 negligible aerosol delivery to the 7.6 Limitation of specific devices lower airway.32 7.6.1 MDI 7.6.2 Small volume nebulizer The MDI cannot be used for the mechani- 7.6.2.1 Differences in placement of cally ventilated patient with the actuator nebulizer in the ventilator circuit can designed for use by the spontaneously result in large variances in drug de- breathing patient with a natural airway. livered to the lung.33 An actuator designed specifically for me- 7.6.2.2 Mass median aerodynamic chanical ventilation is required for actua- diameter (MMAD) and time re- tion of an MDI into the ventilator circuit. quired for treatment may vary with Accessory device adapter design affects type of nebulizer, different models aerosol delivery
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